Danfoss vlt FC 102 Programming Guide

25-21 Override Bandwidth
Range: Function:
are running. The value can be
optimized with increased familiarity
with the system. See
parameter 25-25 OBW Time.
To avoid unintended staging during
the commissioning phase and ne-
tuning of the controller, initially
leave the OBW at the factory
setting of 100% (O). When the
ne-tuning is completed, set the
OBW to the required value. Initial
value of 10% is suggested.
25-22 Fixed Speed Bandwidth
Range: Function:
Size
related*
[ par. 25-20 -
par. 25-21 %]
When the cascade control system
runs normally and the frequency
converter issues a trip alarm, it is
important to maintain the system
head. The cascade controller does
this by continuing to stage/destage
the xed-speed pump on and o.
As keeping the head at the setpoint
would require frequent staging and
destaging when only a xed-speed
pump is running, a wider xed
speed bandwidth (FSBW) is used
instead of SBW. In alarm situations,
or if the start signal on the digital
input goes low, it is possible to
stop the xed speed pumps by
pressing [O] or [Hand On].
If the issued alarm is a trip lock
alarm, the cascade controller stops
the system immediately by cutting
out all the xed-speed pumps. This
is basically the same as emergency
stop (coast/coast inverse command)
for the cascade controller.
25-23 SBW Staging Delay
Range: Function:
15 s* [0 - 3000 s] Immediate staging of a xed-speed
pump is not desirable when a
momentary pressure drop in the
system exceeds the staging
bandwidth (SBW). Staging is
delayed by the length of time
programmed. If the pressure
increases within the SBW before the
timer has elapsed, the timer is
reset.
25-23 SBW Staging Delay
Range: Function:
Illustration 3.78 SBW Staging
Delay
25-24 SBW Destaging Delay
Range: Function:
15 s* [0 - 3000 s] Immediate destaging of a xed-
speed pump is not recommended
when a momentary pressure
increases in the system that
exceeds the staging bandwidth
(SBW). Destaging is delayed by the
length of time programmed. If the
pressure decreases within the SBW
before the timer has elapsed, the
timer is reset.
175ZA671.11
(27-24) SBW destage delay
SBW
SBW
Setpoint
(27-20)
(27-20)
Illustration 3.79 SBW Destaging
Delay
Parameter Descriptions
VLT
®
HVAC Drive FC 102
238 Danfoss A/S © 10/2019 All rights reserved. M0010001
33

Danfoss vlt FC 102 Specifications

General

Brand	Danfoss
Model	vlt FC 102
Category	DC Drives
Language	English